1. Field of the Invention
The present invention is applied to a disc drive apparatus which uses a disc-shaped recording medium for recording and reproduction. The present invention relates to a disc transport apparatus and a disc transport method for transporting a disc-shaped recording medium to a chucking position as well as a disc drive apparatus and a disc drive method.
2. Description of the Related Art
In a widely used disc drive apparatus, a light emitting section emits light to a detection target. A light receiving section detects reflected light and uses its detection output for recording or reproduction of a disc-shaped recording medium.
For example, Patent Document 1: Jpn. Pat. Appln. Laid-Open Publication No. 2001-126286 discloses an optical sensor to detect recording side inclination of a disc-shaped recording medium against an actuator base and another optical sensor to detect the amount of bobbin inclination against the actuator base.
Conventionally, some recording and/or reproduction apparatuses for optical discs and the like are equipped with a transport mechanism and a disc detection apparatus. The transport mechanism transports an optical disc between a recording/reproduction position for recording or reproducing information signals onto an optical disc and a mount/dismount position for mounting or dismounting an optical disc. The disc detection apparatus detects whether or not the optical disc is transported to the recording/reproduction position.
As shown in FIG. 1, this type of disc detection apparatus represents a light detection apparatus 200 using a photointerrupter having a light emitting element and a light receiving element. The light emitting element radiates light to an optical disc's signal recording side. The light receiving element receives reflected light from the signal recording side of the optical disc where the light is radiated. The light detection apparatus 200 is disposed near the recording/reproduction position of an optical disc 201. The light detection apparatus 200 comprises: a photointerrupter 202 facing toward the signal recording side of the optical disc 201 transported to the recording/reproduction position; a direct current power supply Is to drive a light emitting element 203 of the photointerrupter 202; a bias power supply E to supply bias voltage to a light receiving element 204 of the photointerrupter 202; a load resistor R; and an output terminal 205.
In the photointerrupter 202, the light emitting element 203 and the light receiving element 204 are disposed so as to face toward a signal recording side 201a of the optical disc 201 transported to the recording/reproduction position. A light emitting section 203a of the light emitting element 203 and a light receiving section 204a of the light receiving element 204 face toward the signal recording side 201a of the optical disc 201. The light emitting element 203 needs to allow light emitting current Ii to flow in the forward direction. For this purpose, an anode side of the light emitting element 203 is connected to a positive side of the direct current power supply Is. A cathode side thereof is connected to a negative side of the direct current power supply Is. The light receiving element 204 needs to allow output current Io to flow in the forward direction. For this purpose, a collector side of the light receiving element 204 is connected to a positive side of the bias power supply E. An emitter side thereof is connected to a negative side of the bias power supply E via the load resistor R. Both ends of the load resistor R are connected to the output terminal 205 where output voltage Vo is output.
The following describes operations of the light detection apparatus 200 having the above-mentioned configuration. When the light emitting current Ii forward flows through the light emitting element 203 of the light detection apparatus 200, an electron is injected into a p-region and a positive hole is injected into an n-region. These are re-coupled to generate light. The light emitting element 203 generates light from the light emitting section 203a to the signal recording side 201a of the optical disc 201. The light is radiated to the optical disc 201 which then reflects the light at a specified reflection coefficient. The light reflected on the signal recording side 201a of the optical disc 201 is received at the light receiving section 204a of the light receiving element 204. The light receiving element 204 generates an electromotive force due to a semiconducting material to generate a current in the reverse direction. In this manner, photoelectric conversion occurs. In the light detection apparatus 200, output current Io flows in the forward direction of the light receiving element 204. The voltage drops in the load resistor R. This voltage drop is output as output voltage Vo from the output terminal 205. Consequently, detecting output voltage Vo permits a light receiving level to be detected.
There is a difference between light receiving levels depending on whether or not the optical disc 201 is transported to the recording/reproduction position. The light detection apparatus 200 detects this difference to detect whether or not the optical disc 201 is transported to the recording/reproduction position.
The photointerrupter 202 used for the light detection apparatus 200 focuses on the signal recording side 201a of the optical disc 201 transported to the recording/reproduction position. This aims at providing a high light receiving level by more efficiently detecting the reflected light from the signal recording side 201a of the optical disc 201 transported to the recording/reproduction position. The light is focused on the signal recording side of the optical disc 201 when it is transported to the recording/reproduction position. Accordingly, the light receiving element 204 of the light detection apparatus 200 receives the most intense reflected light On the other hand, the light scatters when the optical disc 201 is not transported to the recording/reproduction position. The light receiving element 204 just receives weakly reflected light. Consequently, the light detection apparatus 200 causes a large difference between light receiving levels depending on whether or not the optical disc 201 is transported to the recording/reproduction position. This makes it possible to reliably detect transportation of the optical disc 201.
[Patent Document 2] Jpn. Pat. Appln. Laid-Open Publication No. 991857
The disc drive apparatus described in the above-mentioned patent document 1 and the other ordinary disc drive apparatuses do not use a complicated configuration to transport a disc-shaped recording medium to a chucking section. The disc drive apparatuses are configured to use a disc holder previously sized to a disc diameter and almost horizontally move the disc holder to the chucking section or directly mount the disc-shaped recording medium on the chucking section.
In recent years, there is devised a disc drive apparatus having the following configuration. A disc-shaped recording medium is mounted on a disc holder provided as high as a base unit and is lifted to a chucking position. A chucking section is provided on a drive section and is moved to that position for chucking.
Such disc drive apparatus lifts a disc-shaped recording medium using a mechanism different from the conventional mechanism of directly lifting the disc holder previously sided to the disc diameter. That is to say, the disc drive apparatus lifts a disc-shaped recording medium using three cylinders each having a single point to support a disc-shaped recording medium with diameter 12 cm only, for example. This mechanism may be applicable to a disc drive apparatus that reproduces Super Audio CD with diameter 12 cm only for example. In such disc drive apparatus, however, there is a possibility of tilting or falling a disc-shaped recording medium (circular disc-shaped recording medium) with diameter 8 cm instead of 12 cm, for example, or a triangular, rectangular, or otherwise shaped recording medium (differently shaped recording medium) until it is lifted to the chucking position. If the recording medium remains tilted, the drive section moves to possibly cause a damage to the recording medium or the drive section itself. The recording medium may fall to be damaged.
FIG. 2 shows a recording and/or reproduction apparatus having a light detection apparatus that detects optical disc positions by receiving reflected light from the optical disc's signal recording side. The recording and/or reproduction apparatus is proposed to comprise a disc mount section 211, a disc transport member 212, and a disc rotation drive mechanism 213. The disc mount section 211 is formed to be a circularly recessed plane for mounting an optical disc. The disc transport member 212 is stored at the bottom of the disc mount section 211 and is capable of vertically moving on the disc mount section 211. The disc rotation drive mechanism 213 chucks and rotatively drives the optical disc 201 transported above the disc mount section 211.
The disc mount section 211 of the recording and/or reproduction apparatus 210 has a mounting plane 211a comprising a circularly recessed plane larger than the optical disc 201. The optical disc 201 is mounted at an arbitrary position of the mounting plane 211a. The disc transport member 212 transports the optical disc 201 mounted on the disc mount section 211 and is provided with a plurality of approximately columnar supporting cylinders 212a that support a side of the optical disc 201. The supporting cylinder 212a is stored at the bottom of the mounting plane 211a of the disc mount section 211 and is capable of being elevated on the mounting plane 211a by means of an elevating mechanism (not shown). When the supporting cylinder 212a is lowered to the bottom of the mounting plane 211a, the top surface of the supporting cylinder 212a becomes almost level with the mounting plane 211a to constitute part of the mounting plane 211a. The top surface of the supporting cylinder 212a is formed as a concave sphere to transport the optical disc 201 by supporting its side. The disc rotation drive mechanism 213 is formed with a chucking section 213a to rotatively chuck the optical disc 201 raised to the recording/reproduction position by the disc transport member 212. The chucking section 213a is formed so as to correspond to the height of the recording/reproduction position of the optical disc 201. The chucking section 213a moves along the surface direction of the optical disc 201 to rotatively support the center hole of the optical disc 201.
A user places the optical disc 201 on the disc mount section 211 of the recording and/or reproduction apparatus 210. The disc transport member 212 constitutes part of the mounting plane 211a of the disc mount section 211. When the optical disc 201 is mounted on the disc mount section 211, the supporting cylinder 212a of the disc transport member 212 is raised above the disc mount section 211 by supporting the optical disc 201 that is then lifted to the recording/reproduction position. When transported to the recording/reproduction position, the optical disc 201 is chucked by the chucking section 213a of the disc rotation drive mechanism 213 and is rotatively driven to record or reproduce information signals.
When the recording or reproduction operation terminates and an instruction is issued to eject the optical disc 201, the chucking section 213a of the disc rotation drive mechanism 213 retracts from the principal surface of the optical disc 201. Then, the supporting cylinder 212a of the disc transport member 212 is lowered to the bottom of the mounting plane 211a of the disc mount section 211. As a result, the optical disc 201 is transported to the takeout position. The takeout position is specified slightly above the mounting plane 211a of the disc mount section 211. Since the optical disc 201 is held at the takeout position, the user can easily pick up and eject the optical disc 201. When the optical disc 201 is ejected from the disc mount section 211, the supporting cylinder 212a of the disc transport member 212 is further lowered and is stored at the bottom of the mounting plane 211a of the disc mount section 211.
The recording and/or reproduction apparatus 210 as mentioned above is provided with the light detection apparatus 200 to the bottom of the mounting plane 211a of the disc mount section 211 and on the disc mount section 211. The light detection apparatus 200 detects presence or absence of the optical disc 201 to be moved up and down. The light detection apparatus 200 uses the light emitting element 203 to radiate light to the signal recording side 201a of the optical disc 201. The light detection apparatus 200 also detects presence or absence of the optical disc 201 by using the light receiving element 204 to receive the reflected light from the signal recording side 201a. 
When the optical disc 201 is mounted on the mounting plane 211a of the disc mount section 211, the light detection apparatus 200 receives the reflected light from the signal recording side 201a of the optical disc 201. In this manner, the recording and/or reproduction apparatus 210 detects that the optical disc 201 is mounted on the disc mount section 211. The supporting cylinder 212a of the disc transport member 212 raises the optical disc 201 to the recording/reproduction position.
After completion of the recording or reproduction operation, the optical disc 201 is lowered from the recording/reproduction position to the mounting/dismounting position. When the user ejects the optical disc 201 from the supporting cylinder 212a, the light detection apparatus 200 stops detecting reflected light from the optical disc 201. In this manner, the recording and/or reproduction apparatus 210 can detect ejection of the optical disc 201 and lowers the supporting cylinder 212a to the bottom of the disc mount section 211.
If light with various wavelengths enters from ambiences, however, the light detection apparatus 200 cannot receive the reflected light from the optical disc 201. Even though the optical disc 201 is maintained at the eject position and is not ejected by the user, the recording and/or reproduction apparatus 210 may assume the optical disc 201 to be ejected and may lower the supporting cylinder 212a. 